Filter



FILTER Filed Aug. 25, 1938 2 Sheets-Sheet 1 f a 7n.. .aM/141.

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FILTER Filed Aug. 25, 1938 2 sheetssheet 2 als.

jnvenofas.

44g: S )dig narran sar FUJTER bridge, Mass.

Application August 23, i938, Serial No. 226,308

(Cl. 21d-169) l Claims.

rihis invention relates to filters and especially iilters of the tubulardiamond-weave type set forth in Patent No. 1,958,268, dated May 8, i934,and has for an object an improved construction oi filter elementpermitting faster and better filtering and increasing the capacity, interms Aof the total quantity of uid iiltered, of the filter elementbefore the passages thereof have been clogged.

The lter element of the above patent is tubular comprising a ioraminouscore upon which is wound a multiplicity of layers of spaced convolutionsof a napped strand applied in crisst cross fashion to form a pluralityoi diamond shaped ltering passages through the side wall of the elementthrough which the liquid to be filtered iscaused to pass, the strandsbeing napped during the-progress of winding to form iibres which occupythe passages and catch impurities in the liquid being ltered.

Due to the manner of winding the strand the two axes of a cross-sectionof each diamond shaped passage lie respectively circumferentially andaxially of the element, the circumferentially axis increasing in lengthas the winding progresses and the axial axis remaining constant. in theelement or tube filter of the above patent the direction of the nappingis circumferential so that the napped fibres, which are carried acrossthe diamond shaped ltering passages and are bound down by the overlaidstrands, lie circumferentially of the tube and along the circumferentialaxis of the diamond shaped liltering passages. Since for various reasonsnot necessary'l to explain here it is most practical in most cases tohave at the start of the winding a diamond shape in which thecircumferential axis is at least as long as the axial axis, and since asthe winding progresses the circumferential axis increases in lengthwhile the axial axis remains constant, it results that throughout asubstantial part of the thickness of the windting the circumferentialaxis is longer than the axial axis. In view of these facts and in vie'wof the further fact that it is difficult tolncrease beyond a certainpoint the average length of the napped ilbre, the circumferential axisof the diamonds of tubes made under the above patent have to berelatively short. which means a small cross-sectional area of passage,in order that a sufficient amount of the circumerentially riapped fibresmay be carried completely across the passage.

in commercial practice we have found that with tunnels of small area, orsufficiently small to enable there being carriedcompletely across thetunnels a suiilcient amount of the napped fibres to secure the lnenessof i'lltration desired, the ow of the iiltered liquidthrough the tunnelsof a single filter tube is insuiiicient to permit the free use of thetubes in certain applications on account of the number of tubesrequired.

We have discovered, however, a new method of forming and drawing thenapped ilbres across the tunnels which materially increases the amountof the napped fibres that are carried completely across the tunnelpassages, thereby increasing the density of the napped fibres drawncompletely across the tunnels, which improves the filtration, andallowing tunnels of larger cross-section area to be used, which enlargesthe capacity of the illter tubes as respects both the rate of flow ofthe filtered liquid and the total amount of the liquid which may bbefiltered before the tunnel passages of the tubes have become clogged.We' have found that if the method of napping heretofore used is entirelychanged and instead of drawing the napped fibres circumferentially ofthe tube, a belt or other means is used to draw the nap axially of thetube there will be a very unexpected irnprovement in result in that thelibres as a result of .the component of the axial napping movement andthe circumerential rotation of the tube will be drawn more nearly in thedirection of the shortest distance across the tun'- nels and therefore agreater amount of the y napped bres will reach entirely across thetunnel and be locked in place by the lstrands subsequently laid. Such alter element and the method of making it constitutes an object of thepresent invention. l

Another object of the invention is the method oi napping by winding therotating tube While in contact with a napping belt moving in the axialdirection of the tube, the speed of the belt throughout the windingprocess being preferably as great or greater than the circumferentialspeed of the tube so that the nappedflbres are laid at an angle ofinclination with the axis of the tube approximating the direction ofshortest distance between the sidesJ of the diamond shaped passages.

It is a further object oi' the present invention to provide a filteringtube with a plurality of layers of passage-traversing napped fibres thatlie at different anglesvso that an impurity, as a thin flake, in theliquid being filtered and that may be aligned with the libres of onelayer and hence may pass therebetween, is caused to encounter an underlayer of otherwise disposed fibres and hence will be caught by and lodgeupon such fibres.

Another object of the invention is the method of making such a tube withthe layers of parallel napped fibres having a relatively crossedrelation to each other by repeated reversals of the direction of nappingduring the progress of the tube winding operation.

Another object of the invention is to increase the amount of nappedfibre without distorting the diamond shaped filtering passages and tomaintain a greater uniformity of napped fibre throughout a particulartube and throughout all tubes of a particular type. 'I'hese results arebetter accomplished by axial napping rather than by circumferentialnapping for in axial napping the napping wires are drawn across thestrands rather than along the strands as in circumferential napping,thereby raising more nap, and furthermore the nap is more uniformthroughout the element due to the better control of the pressure of theface of the napping element on the tube.

A yet further object is generally to improve the construction andperformance of filter elements. f

Fig. 1 is a plan view of a filter'eiement embodying the presentinvention.

Fig. 2 is a cross-sectional view of the filter element, taken along line2--2 of Fig. l.

Fig. 3 is an enlarged diagrammatic plan view of a diamond shaped filterpassage and the filter fibres arranged in accordance with the presentinvention.

Fig. 4 is a view similar to Fig. 3 but in a different location along thelength of the passage and illustrating the opposite inclination of thefiltering fibres.

Fig. 5 is a front elevation of a machine for making the filter elementof Fig. 1.

Fig. 6 is a side elevation of the napping frame of Fig. 5.

Fig. '7 is a plan detail of the pressure plate of Fig. 6.

Fig. 8 is a sectional detail takenl along ine 8-8 of Fig. 7 andillustrating the manner of adjusting said pressure plate.

Fig. 9 is a circuit diagram of the timed reversing means for the beltdriving motor.

As illustrated in Figs. 1 through 4, the tubular filter element 9 iscomposed of a plurality of layers of fibrous strands I0, morespecifically soft yarn or roving, wound in a diamondmeave upon apervious core tube II formed of an open mesh wire fabric or netting in aplurality of layers of axially spaced and criss-crossed convolutions'that are superposed in the several layers, thereby formingdiamond-shaped apertures I2 between the crossed strands that are inalignment, at least in part, to form filtering passages or tunnels I3through the winding from the circumference to the pervious core.

Due to the manner of winding the roving one axis of a cross-section ofthe diamond-shaped passage I2 lies substantially in the circumference ofthe filter while the other axis is parallel with the axis of the filter.For reasons already explained the circumferentlally disposed axes of thepassages are longer than the axially disposed axes, for a substantialpart of the thickness of the element.

In accordance withl the present invention the roving composing thefilter element is napped in a direction lengthwise of the axis of thefilter ele- GII illustrated in Figs. 5 and 6. The machine so faias thewinding of the strands is concerned, may be essentially a well knownUniversal winding machine which includes a rotatable mandrel 22 on whichthe tube II of the filter is placed for winding on the yarn, but anysimilar machine may be used. The machine has a yarn guide 24 which isreciprocated in front of 'the'maMrel 22 in timed relation with therotation of the mandrel to lay on the strands in the manner aboveexplained.

The napping of the strands is accomplished by means including a carriage2l disposed behind the mandrel and movable on ways 28 towards and awayfrom the mandrel. The carriage supports a pair of pulleys I0 betweenwhich a napping belt 32 as of card clothing is extended. One of thepulleys is driven by a chain 34 and sprocket 36 from an electric motor38 carried by the carriage. The carriage is provided with a pressureplate 3! the face of which is at right angles to the work face of thenapping belt and is adapted to bear against the tubular filter element 9on the mandrel, the pressure plate being so positioned with respect tothe work face of the belt, the

axis of the mandrel and the path of movement of the carriage that thewires of the belt will be always maintained in substantially the samerelative contact with the surface of the filter element as it increasesin diameter.

In order that the pressure plate can always be kept in proper position,its position can be adiusted to take care of wear in any moving parts ofthe machine by movement of the screws 4l, l2, and 44 at each end of theplate. The screw 40 is passed loosely through the plate and isscrewthreaded into the carriage. The screws 42 and 44, disposed onopposite sides of the screw Il, are loosely disposed in said plate andare screwthreaded in the carriage and have outstanding shoulders 45which bear against the under face of the plate to move the plate Ilrelative to the carriage 26. l

The carriage is urged toward the tube by l lelmental gear 48 fixed to a.shaft 4l supported by the frame of the winding machine. The gear mesheswith a rack 50 of the carriage and is urged for rotation in a directionto move the carriage toward the tube by a rearwardly extended arm I2fixed to the shaft 48 and supporting a weight II adjustable along thelength thereof. The angularity of the arm 52 preferably is such that theweight IB is caused to exert more pressure on theV carriage against thetube as the tube builds up in diameter and the carriage moves backward.

Thus just prior to the winding operation the plate I9 bears against thecore II.. which has been positioned on the rotatable mandrel 22 (shownin dotted lines in Fig. 6), under the infiuence of the weight I8 whichtends to move the carriage 2B to the right (Fig. 6). By adjusting theplate 39 by means of screws 42 and 44 the relationship of the respectivedistances of the face of the pressure plate 39 and of the face of thebelt 32, namely, the ends of the wires, from the axis of mandrel 22, maybe varied. The variation of the relationship of these distances willdetermine the amountof the engagement of the Wires of the belt 32 withthe tubular cylindrical filter element 9 during the winding process. As

f the diameter of the lter element increases during winding this amountof engagement of the wires of the belt with the filter element willremain substantially the same throughout the winding process, subject tothe effect of any progressive increased pressure of the pressure plate39 against the filter element caused by the increased leverage of theweight 56 as the carriage 26 is forced away from the axis of mandrel 22by contact of the filter element, as it is wound, with the pressureplate 39. At the conclusion of the winding process the filter elementassumes the diameter indicated by the dotted circular line 9 in Fig. 6and the belt 32 and pulley 30 (Fig. 6) assumes the dotted line positionindicated in Fig. 6. The napping belt 32 is suiiiciently wide to engagethe periphery of the tube from its smallest to its largest diameter asthe tube builds up in diameter and its point of contact with the belttravels upwardly on the belt. The pass of the belt that confronts thetube is long enough to engage it from end to end. With this arrangementas the convolutions are wound on the tube they come in contact with thewires of the travelling belt which brush fibres in a direction axiallylof the tube to project away from the convolutions across the aperturesbetween the convolutions.

Since the direction of the lay of the napped fibres is along thecomponent of the belt speed and the peripheral speed of the tube, theangle which the napped fibres make with the tube axis depends upon therelation between the belt speed and the peripheral speed of the tube atany part thereof. This angle is smaller at the core than 'at thecircumference of the finished tube since the peripheral speed of thetube increases as the winding builds up, the fibres of the successivelayers changing in angle progressively from the core to thecircumference, the amount of the total change between the core and thecircumference depending upon the ratio of the length of the diameter ofthe core to the thickness of the wall of the tube. The speed of thenapping belt and the speed of the mandrel carrying the tube preferablybear a relationship one to the other such as to cause the napped fibresin the outside layer of yarn, where the area of the diamond shapedtunnel passages is the greatest, to lie anproximately in the directon ofthe shortest distance between the sides of the diamond. By being laidmainly in the direction of the shortest distance across the passages,the napped fibres, or most of them, completely traverse the passages sothat their ends are bound down on the tube by the overlaid strand.'I'his results in a very satisfactory filter and represents a markedimprovement over a filter tube in which the nap is raised and laidcircumferentially of the tube. The effectiveness of the filtration isincreased because. of the increased amount of napped fibre drawncompletely across the passages and held in place by the overlaid strandsof yarn. The passages' also can be made larger than heretofore therebvpermitting a more rapid iiow of the fluid to be filtered through thefilter and increasing the total amount of the fluid which the filterelement can handle before its life is exhausted by the clogging of thetunnel passages.

The electric motor 38 is of the reversible type and may be automaticallyreversed periodically by the means illustrated in Fig. 9 so that thedirection of napping is periodically reversed. The reversal is intendedto take place at such times as to give the results desired and'may takeplace at approximately each layer or otherwise.

The motor 38 is illustrated in Fig. 9 as being a three phase motorenergized from a power source 6D through reversing switches 62 and 64respectively energized through a double throw switch 66 from a line 68.Said switch 66 is, operated by a cam disc having high and low peripheral-portions 10 and 12 and intervening inclined portions 13. When the'highportion l0 is under the switch 66 the winding 14 is energized to obtainone direction of rotation of the belt driving motor 38 and when the lowportion 12 is under the switch the winding 1B is energized to obtain theopposite direction of rotation of the motor. The inclined portions 13 ofthe cam hold the control circuit open sufficiently long to permit themotor to lose considerable speed before reversal. The cam is driven'atsuitable speed by a timing motor 18 energized from the circuit 68.

By reason of the reversals of napping during the winding of the tube thebres in different layers of nap in the filtering tunnels ae oppositelyinclined. rFor instance, the lay of the fibres in one section of atunnel may be as illustrated in Fig. 3, while the lay of the fibres inanother partvof the same tunnel may be as illustrated in Fig. 4. Thisarrangement increases the efficiency of filtering as, for instance, athin flake of an impurity may be aligned with one set of fibres andhence pass therethrough but .will be crosswise or at least at an anglewith another set; of fibres and hence unable to pass between fibres ofthis set and hence will be caught byl the fibres. 'I'his action of thefilter takes place to a greater or less extent even without reversal ofthe directiony of, nappingl by reasoncf the progressive change of angleof lay of the fibres from the outside to the inside of the winding ashas been explained above.

The reversal of the direction of napping also improves the'lteringaction in an additional manner.- With large apertures the nap may bethinnest at or about, the apex of the diamond opposite the sides fromwhich the fibres start. By vthe reversal of napping, however, a thinsection of nap of one layer is overlaid by a thick section of nap ofanother layer so that any particle that could pass through a thinsection has to travel such a tortuous path in going from one thinsection to another that it is surely trapped before it can emerge fromthe filter. Likewise there is a similar staggering of the areas wherethe ends of the napped bres are held in place by being embedded in thestrands `from which they are drawn and of the areas where the oppositeends of the napped fibres are held in place by being bound down by theoverlaid strands.

The reversal of direction of napping also reysults in an intermeshing ofthe napped fibres formed in napping the layer of the strands which isbeing wound when the reversal of the direction of napping occurs. Thisimproves the filtration materially in the case of certain liquids, suchas oils. Reversal of direction of the napping also increases both theamount and uniformity of napped fibre since the yarn is napped on bothsides instead of only on one side and also any diminution in napped bredue to the twist of the yarn being inclined towards the movement ofpassage sides forming angles which face the same' end of the tubularelement toward strands lying in the opposite pairs of adjacent passagesides 'forming angles which face the other end of the tulml r element.

.ii tubular filter element as claimed in claim i. wherein the generaldirection of a preponderfe ci; the fibers so extending between strandsof "essively changes from layer to layer least a portion of thethickness of veine tubular filter element as claimed in claim wherein apreponderance of the fibers so extending between strands oi. one layerare oppositely inclined to a preponderance of the fibers so extendingbetween strands of another layer.

A tubular filter element as claimed in claim l wherein at least somefibers extend from ends lying in said first-mentioned pairs of "e sidesacross the passages and are bound ion hy overand under-lying strandslysaid second-mentioned pairs of passage :z i, and other fibers extendfrom said overand miren-lying strands across the same passages in e,contrariwise direction and are similarly bound in position by strandslying in said first-mentioned pairs of passage sides.

huler filter element as claimed in claim ri at least some fibers extendKfrom sitnds lying in said first-mentioned pairs of sides across thepassages and are bound in position by overand under-lying strands lyingin said second-mentioned pairs of passage sides, and other fibers extendfrom said overand under-lying strands across the same passages iucontrariwise direction and are similarly hou-,id in position by strandslying in said firsttioned pairs of passage sides, the angles 'd by vthefibers extending contrarlwise to i, other across the passages changingproiy through at least a portion of the thickradially extendingdiamond-shaped filuassages into which fibers extend from towardstrands-of the same layer, a prederance of the fibers so extendingbetween nds of at least one layer extending in direcins inclinedrespectively to the directions of the line joining strands of such layerwhich iu a pair of opposite parallel sides of the lar passage into whichthe fibers extend, id said fiber directions and said shortest linections respectively approaching each other i progressively lesseninginclination therebetween. from a relativelyinner to a relatively outerlayer of at least a portion of the thickness of the element.

The method of making a tubular filter element which comprises windingfibrous strand t0 u form upon a revolving support a plurality of layersof spaced crossed convolutions of brous strands forming diamond-shapedpassages through the element, and napping the fibrous strands in adirection between a direction around the circumference and a directionparallel to the axis of the filter as the winding operation progresses.I

8. The method of making a tubular filter element as in claim 7, whichincludes the step of reversing the direction of napping during theprocess of winding to change the direction of the lay of the fibres andgiving successive sheets of napping a relatively crossed relation.

9. The method of making a tubular filter element which comprises windinga fibrous strand to form upon a revolving support a plurality of layersof spaced crossed convolutions of fibrous strands forming diamond-shapedpassages through the winding, and napping the fibrous strands during theprocess of winding by contact therewith of moving a napping member in adirection parallel to the axis of the filter.

10. The method of making a tubular filter element as in claim 9, whichincludes controlling the movement of the napping member to change theangle of lay of napped fibers from the inside to the outside of thefilter.

l1. The method of making a tubular filter element which compriseswinding a fibrous strand to form upon a vrevolving support a pluralityof layers of spaced crossed convolutions of fibrous strands formingthrough the winding, napping the fibrous strands during the process ofwinding by contact therewith of moving a napping member in aA directionparallel to the axis of the filter, and reversing the direction ofmovement of the napping mem ber during the process of winding.

12. The method of making a tubular filter element which comprisesWinding a fibrous strand to form upon a revolving support a plurality oflayers of spaced crossed convolutions of fibrous strands formingpassages through the winding, napping the fibrous strands during theprocess of winding by moving a strand-contacting napping member in adirection parallel to the axis of the filter and increasing the pressureof the napping member against the strands as winding progresses.

13. The method of making a tubular filter ele` ment which compriseswinding a fibrous strand upon a revolving support to form a plurality oflayers of crossed axially spaced convolutions of fibrous strands formingopenings through the layers of the winding, and napping the fibrousstrands of separate layers during the process of winding by contacttherewith of a movable napping member moving in a direction from end toend of said revolving support to lay napped fibers of a succeedingrelatively outer layer in crossed relation with respect to napped fibersof a preceding relatively inner layer.

14. The method of making a tubular filter element which'compriseswinding a fibrous strand upon a revolving support to form a plurality oflayers of crossed axially spaced convolutions of fibrous strands formingdiamond-shaped passages through the winding and napping the fibrouslstrands of separate layers during the process of winding by contacttherewith of a napping member moving in a direction from end to end ofsaid revolving support to lay napped fibers crosswise of the passagesand at an angle to the axis of the filter, with fibers of one layer in apassage diamond-shaped passagesv lying in crossed relation with respectto berS to the axis of the lter element to extend bers of another layerin the sarne passage. into the passages from and towards strands of 15.The method of making a tubular filter elethe same layer in directionswhich, as the windment which comprises winding a brous strand ingproceeds, become less inclined, throughout upon a revolving support toform a plurality of 5 atleast a portion of the thickness of the element.

circumferential layers of spaced cross convoluto the direct-ions of theshortest line joining tions of brous strands providing a plurality ofstrands of such layer lying in a pair of opposite l radially extendingdiamond-shaped filtering pasparallel sides of the particular passageinto which sages and napping the brous strands during the the fibersextend. process of winding by Contact therewith of a 10 MERRILL G.HASTINGS.

napping member moving in a direction parallel H. J. HAYWARD.

